The use of greenhouses is known, e.g., at places with unsuitable or suboptimal climatic circumstances in order to increase the harvest, to allow for the cultivation of specific crops, or to protect plants from extreme weather conditions. For this purpose, two major objects are often focused on. On the one hand, suitable conditions for growth such as soil conditions, soil humidity, and indoor climate (e.g., lighting, air humidity, temperature, and air movement) must be created. On the other hand, a greenhouse must be designed such that it withstands the static loads that occur due to the structure and design of the greenhouse itself, the planting, and the environmental impacts.
For this purpose, a common greenhouse customarily comprises a supporting structure (e.g., made of wood, steel, or aluminum) resting on a base. Said supporting structure is provided with a translucent roofing made of glass panes, plastic films (e.g., of PVC or PE), or plastic plates (e.g., plastic glass (PMMA), polycarbonate, fiber-reinforced polyester, or PVC). Cultivated areas for plants to be grown are provided in the greenhouse.
With respect to the cultivated areas, difference is made between, e.g., types of beds, tables, or suspended constructions. Floor beds are directly connected to the natural soil, whereas the cultivated substrate layer of in-ground beds is separated from the natural soil by an impervious layer made of concrete or foil. In raised beds, the culture medium is embedded into troughs generally made of concrete so that the substrate layer does not come into contact with the natural soil, either. The cultivation of plants on tables comes into use with potted plants, wherein the tables are either stationary or movable for increased space utilization by eliminating aisles. Although hangers may allow for increased usable spaces by using spaces above the beds or tables, they entail an impedance of the incident light on lower cultivated areas, and crop maintenance is more cumbersome.
What is more, many greenhouses are provided with ventilation means in order to influence the oxygen and carbon dioxide contents of the greenhouse air and to regulate the temperature. Irrigation and/or sprinkling systems, means for shading or darkening, lighting systems for artificially lighting crops, CO2 fertilization means for carbon dioxide fertilization, and combined heat and power plants are further constituents of greenhouses.
Since in known greenhouses the floor areas or plant tables or simple suspended constructions or shelf constructions are primarily used, the degree of volume utilization of conventional greenhouses is rather small.